Дисертації з теми "Perceptual Quality Assessment"
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Dhakal, Prabesh, Prabhat Tiwari, and Pawan Chan. "Perceptual Video Quality Assessment Tool." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2576.
Повний текст джерелаIn our research work, we have designed the tool that can be used to conduct a mass-scale level survey or subjective tests. ACR is the only method used to carry out the subjective video assessment. The test is very useful in the context of a video streaming quality. The survey can be used in various countries and sectors with low internet speeds to determine the kind of video or the compression technique, bit rate, or format that gives the best quality.
0700627491, 0760935352
Yang, Kai-Chieh. "Perceptual quality assessment for compressed video." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3284171.
Повний текст джерелаTitle from first page of PDF file (viewed Mar. 14, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 149-156).
Rix, Antony W. "Perceptual techniques in audio quality assessment." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/14286.
Повний текст джерелаSavvides, Vasos E. "Perceptual models in speech quality assessment and coding." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/36273.
Повний текст джерелаZhu, Shu-Yu. "Perceptual wavelet coding and quality assessment for still image." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ53450.pdf.
Повний текст джерелаHuynh-Thu, Quan. "Perceptual quality assessment of communications-grade video with temporal artefacts." Thesis, University of Essex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502128.
Повний текст джерелаOsberger, Wilfried. "Perceptual vision models for picture quality assessment and compression applications." Thesis, Queensland University of Technology, 1999.
Знайти повний текст джерелаGuarnieri, Gabriele. "High dynamic range images: processing, display and perceptual quality assessment." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3121.
Повний текст джерелаThe intensity of natural light can span over 10 orders of magnitude from starlight to direct sunlight. Even in a single scene, the luminance of the bright areas can be thousands or millions of times greater than the luminance in the dark areas; the ratio between the maximum and the minimum luminance values is commonly known as dynamic range or contrast. The human visual system is able to operate in an extremely wide range of luminance conditions without saturation and at the same time it can perceive fine details which involve small luminance differences. Our eyes achieve this ability by modulating their response as a function of the local mean luminance with a process known as local adaptation. In particular, the visual sensation is not linked to the absolute luminance, but rather to its spatial and temporal variation. One consequence of the local adaptation capability of the eye is that the objects in a scene maintain their appearance even if the light source illuminating the scene changes significantly. On the other hand, the technologies used for the acquisition and reproduction of digital images are able to handle correctly a significantly smaller luminance range of 2 to 3 orders of magnitude at most. Therefore, a high dynamic range (HDR) image poses several challenges and requires the use of appropriate techniques. These elementary observations define the context in which the entire research work described in this Thesis has been performed. As indicated below, different fields have been considered; they range from the acquisition of HDR images to their display, from visual quality evaluation to medical applications, and include some developments on a recently proposed class of display equipment. An HDR image can be captured by taking multiple photographs with different exposure times or by using high dynamic range sensors; moreover, synthetic HDR images can be generated with computer graphics by means of physically-based algorithms which often involve advanced lighting simulations. An HDR image, although acquired correctly, can not be displayed on a conventional monitor. The white level of most devices is limited to a few hundred cd/m² by technological constraints, primarily linked to the power consumption and heat dissipation; the black level also has a non negligible luminance, in particular for devices based on the liquid crystal technology. However, thanks to the aforementioned properties of the human visual system, an exact reproduction of the luminance in the original scene is not strictly necessary in order to produce a similar sensation in the observer. For this purpose, dynamic range reduction algorithms have been developed which attenuate the large luminance variations in an image while preserving as far as possible the fine details. The most simple dynamic range reduction algorithms map each pixel individually with the same nonlinear function commonly known as tone mapping curve. One operator we propose, based on a modified logarithmic function, has a low computational cost and contains one single user-adjustable parameter. However, the methods belonging to this category can reduce the visibility of the details in some portions of the image. More advanced methods also take into account the pixel neighborhood. This approach can achieve a better preservation of the details, but the loss of one-to-one mapping from input luminances to display values can lead to the formation of gradient reversal effects, which typically appear as halos around the object boundaries. Different solutions to this problem have been attempted. One method we introduce is able to avoid the formation of halos and intrinsically prevents any clipping of the output display values. The method is formulated as a constrained optimization problem, which is solved efficiently by means of appropriate numerical methods. In specific applications, such as the medical one, the use of dynamic range reduction algorithms is discouraged because any artifacts introduced by the processing can lead to an incorrect diagnosis. In particular, a one-to-one mapping from the physical data (for instance, a tissue density in radiographic techniques) to the display value is often an essential requirement. For this purpose, high dynamic range displays, capable of reproducing images with a wide luminance range and possibly a higher bit depth, are under active development. Dual layer LCD displays, for instance, use two liquid crystal panels stacked one on top of the other over an enhanced backlight unit in order to achieve a dynamic range of 4 ÷ 5 orders of magnitude. The grayscale reproduction accuracy is also increased, although a “bit depth” can not be defined unambiguously because the luminance levels obtained by the combination of the two panels are partially overlapped and unevenly spaced. A dual layer LCD display, however, requires the use of complex splitting algorithms in order to generate the two images which drive the two liquid crystal panels. A splitting algorithm should compensate multiple sources of error, including the parallax introduced by the viewing angle, the gray-level clipping introduced by the limited dynamic range of the panels, the visibility of the reconstruction error, and glare effects introduced by an unwanted light scattering between the two panels. For these reasons, complex constrained optimization techniques are necessary. We propose an objective function which incorporates all the desired constraints and requirements and can be minimized efficiently by means of appropriate techniques based on multigrid methods. The quality assessment of high dynamic range images requires the development of appropriate techniques. By their own nature, dynamic range reduction algorithms change the luminance values of an image significantly and make most image fidelity metrics inapplicable. Some particular aspects of the methods can be quantified by means of appropriate operators; for instance, we introduce an expression which describes the detail attenuation introduced by a tone mapping curve. In general, a subjective quality assessment is preferably performed by means of appropriate psychophysical experiments. We conducted a set of experiments, targeted specifically at measuring the level of agreement between different users when adjusting the parameter of the modified logarithmic mapping method we propose. The experimental results show a strong correlation between the user-adjusted parameter and the image statistics, and suggest a simple technique for the automatic adjustment of this parameter. On the other hand, the quality assessment in the medical field is preferably performed by means of objective methods. In particular, task-based quality measures evaluate by means of appropriate observer studies the clinical validity of the image used to perform a specific diagnostic task. We conducted a set of observer studies following this approach, targeted specifically at measuring the clinical benefit introduced by a high dynamic range display based on the dual layer LCD technology over a conventional display with a low dynamic range and 8-bit quantization. Observer studies are often time consuming and difficult to organize; in order to increase the number of tests, the human observers can be partially replaced by appropriate software applications, known as model observers or computational observers, which simulate the diagnostic task by means of statistical classification techniques. This thesis is structured as follows. Chapter 1 contains a brief background of concepts related to the physiology of human vision and to the electronic reproduction of images. The description we make is by no means complete and is only intended to introduce some concepts which will be extensively used in the following. Chapter 2 describes the technique of high dynamic range image acquisition by means of multiple exposures. In Chapter 3 we introduce the dynamic range reduction algorithms, providing an overview of the state of the art and proposing some improvements and novel techniques. In Chapter 4 we address the topic of quality assessment in dynamic range reduction algorithms; in particular, we introduce an operator which describes the detail attenuation introduced by tone mapping curves and describe a set of psychophysical experiments we conducted for the adjustment of the parameter in the modified logarithmic mapping method we propose. In Chapter 5 we move to the topic of medical images and describe the techniques used to map the density data of radiographic images to display luminances. We point out some limitations of the current technical recommendation and propose an improvement. In Chapter 6 we describe in detail the dual layer LCD prototype and propose different splitting algorithms for the generation of the two images which drive the two liquid crystal panels. In Chapter 7 we propose one possible technique for the estimation of the equivalent bit depth of a dual layer LCD display, based on a statistical analysis of the quantization noise. Finally, in Chapter 8 we address the topic of objective quality assessment in medical images and describe a set of observer studies we conducted in order to quantify the clinical benefit introduced by a high dynamic range display. No general conclusions are offered; the breadth of the subjects has suggested to draw more focused comments at the end of the individual chapters.
XXI Ciclo
1982
Oh, Joonmi. "Human visual system informed perceptual quality assessment models for compressed medical images." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368425.
Повний текст джерелаChintala, Bala Venkata Sai Sundeep. "Objective Perceptual Quality Assessment of JPEG2000 Image Coding Format Over Wireless Channel." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-17785.
Повний текст джерелаMasaki, Asako. "Optimizing acoustic and perceptual assessment of voice quality in children with vocal nodules." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54666.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 105-109).
Few empirically-derived guidelines exist for optimizing the assessment of vocal function in children with voice disorders. The goal of this investigation was to identify a minimal set of speech tasks and associated acoustic analysis methods that are most salient in characterizing the impact of vocal nodules on vocal function in children. Hence, a pediatric assessment protocol was developed based on the standardized Consensus Auditory Perceptual Evaluation of Voice (CAPE-V) used to evaluate adult voices. Adult and pediatric versions of the CAPE-V protocols were used to gather recordings of vowels and sentences from adult females and children (4-6 and 8-10 year olds) with normal voices and vocal nodules, and these recordings were subjected to perceptual and acoustic analyses. Results showed that perceptual ratings for breathiness best characterized the presence of nodules in children's voices, and ratings for the production of sentences best differentiated normal voices and voices with nodules for both children and adults. Selected voice quality-related acoustic algorithms designed to quantitatively evaluate acoustic measures of vowels and sentences, were modified to be pitch-independent for use in analyzing children's voices. Synthesized vowels for children and adults were used to validate the modified algorithms by systematically assessing the effects of manipulating the periodicity and spectral characteristics of the synthesizer's voicing source.
(cont.) In applying the validated algorithms to the recordings of subjects with normal voices and vocal nodules, the acoustic measure tended to differentiate normal voices and voices with nodules in children and adults, and some displayed significant correlations with the perceptual attributes of overall severity of dysphonia, roughness, and/or breathiness. None of the acoustic measures correlated significantly with the perceptual attribute of strain. Limitations in the strength of the correlations between acoustic measures and perceptual attributes were attributed to factors that can be addressed in future investigations, which can now utilize the algorithms that were developed in this investigation for children's voices. Preliminary recommendations are made for the clinical assessment of pediatric voice disorders.
by Asako Masaki.
Ph.D.
MONTEIRO, Estêvão Chaves. "Shifted Gradient Similarity: A perceptual video quality assessment index for adaptive streaming encoding." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17359.
Повний текст джерелаMade available in DSpace on 2016-07-13T18:59:10Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Shifted Gradient Similarity - A perceptual video quality assessment index for adaptive streaming encoding.pdf: 5625470 bytes, checksum: 8ec1d179ec4cca056eb66609ba5791a0 (MD5) Previous issue date: 2016-03-04
Adaptive video streaming has become prominent due to the rising diversity of Web-enabled personal devices and the popularity of social networks. Common limitations in Internet bandwidth, decoding speed and battery power available in such devices challenge the efficiency of content encoders to preserve visual quality at reduced data rates over a wide range of display resolutions, typically compressing to lower than 1% of the massive raw data rate. Furthermore, the human visual system does not uniformly perceive losses of spatial and temporal information, so a simple physical objective model such as the mean squared error does not correlate well with perceptual quality. Objective assessment and prediction of perceptual quality of visual content has greatly improved in the past decade, but remains an open problem. Among the most relevant psychovisual quality metrics are the many versions of the Structural Similarity (SSIM) index. In this work, several of the most efficient SSIM-based metrics, such as the Multi-Scale Fast SSIM and the Gradient Magnitude Similarity Deviation (GMSD), are decomposed into their component techniques and reassembled in order to measure and understand the contribution of each technique and to develop improvements in quality and efficiency. The metrics are applied to the LIVE Mobile Video Quality and TID2008 databases and the results are correlated to the subjective data included in the databases in the form of mean opinion scores (MOS), so each metric’s degree of correlation indicates its ability to predict perceptual quality. Additionally, the metrics’ applicability to the recent, relevant psychovisal rate-distortion optimization (Psy-RDO) implementation in the x264 encoder, which currently lacks an ideal objective assessment metric, is investigated as well. The “Shifted Gradient Similarity” (SG-Sim) index is proposed with an improved feature enhancement by avoiding a common unintended loss of analysis information in SSIM-based indexes, and achieving considerably higher MOS correlation than the existing metrics investigated in this work. More efficient spatial pooling filters are proposed, as well: the decomposed 1-D integer Gaussian filter limited to two standard deviations, and the downsampling Box filter based on the integral image, which retain respectively 99% and 98% equivalence and achieve speed gains of respectively 68% and 382%. In addition, the downsampling filter also enables broader scalability, particularly for Ultra High Definition content, and defines the “Fast SG-Sim” index version. Furthermore, SG-Sim is found to improve correlation with Psy-RDO, as an ideal encoding quality metric for x264. Finally, the algorithms and experiments used in this work are implemented in the “Video Quality Assessment in Java” (jVQA) software, based on the AviSynth and FFmpeg platforms, and designed for customization and extensibility, supporting 4K Ultra-HD content and available as free, open source code.
Cada vez mais serviços de streaming de vídeo estão migrando para o modelo adaptativo, devido à crescente diversidade de dispositivos pessoais conectados à Web e à popularidade das redes sociais. Limitações comuns na largura de banda de Internet, velocidade de decodificação e potência de baterias disponíveis em tais dispositivos desafiam a eficiência dos codificadores de conteúdo para preservar a qualidade visual em taxas de dados reduzidas e abrangendo uma ampla gama de resoluções de tela, tipicamente comprimindo para menos de 1% da massiva taxa de dados bruta. Ademais, o sistema visual humano não percebe uniformemente as perdas de informação espacial e temporal, então um modelo objetivo físico simples como a média do erro quadrático não se correlaciona bem com qualidade perceptível. Técnicas de avaliação e predição objetiva de qualidade perceptível de conteúdo visual se aprimoraram amplamente na última década, mas o problema permanece em aberto. Dentre as métricas de qualidade psicovisual mais relevantes estão muitas versões do índice de similaridade estrutural (Structural Similarity — SSIM). No presente trabalho, várias das mais eficientes métricas baseadas em SSIM, como o Multi-Scale Fast SSIM e o Gradient Magnitude Similarity Deviation (GMSD), são decompostas em suas técnicas-componentes e recombinadas para se obter medidas e entendimento sobre a contribuição de cada técnica e se desenvolver aprimoramentos à sua qualidade e eficiência. Tais métricas são aplicadas às bases de dados LIVE Mobile Video Quality e TID2008 e os resultados são correlacionados aos dados subjetivos incluídos naquelas bases na forma de escores de opinião subjetiva (mean opinion score — MOS), de modo que o grau de correlação de cada métrica indique sua capacidade de predizer qualidade perceptível. Investiga-se, ainda, a aplicabilidade das métricas à recente e relevante implementação de otimização psicovisual de distorção por taxa (psychovisual rate-distortion optimization — Psy-RDO) do codificador x264, ao qual atualmente falta uma métrica de avaliação objetiva ideal. O índice “Shifted Gradient Similarity” (SG-Sim) é proposto com uma técnica aprimorada de realce de imagem que evita uma perda não-pretendida de informação de análise, comum em índices baseados em SSIM, assim alcançando correlação consideravelmente maior com MOS comparado às métricas existentes investigadas neste trabalho. Também são propostos filtros de consolidação espacial mais eficientes: o filtro gaussiano de inteiros 1-D decomposto e limitado a dois desvios padrão e o filtro “box” subamostrado baseado na imagem integral, os quais retém, respectivamente, 99% e 98% de equivalência e obtém ganhos de velocidade de, respectivamente, 68% e 382%. O filtro subamostrado também promove escalabilidade, especialmente para conteúdo de ultra-alta definição, e define a versão do índice “Fast SG-Sim”. Ademais, verifica-se que o SG-Sim aumenta a correlação com Psy-RDO, indicando-se uma métrica de qualidade de codificação ideal para o x264. Finalmente, os algoritmos e experimentos usados neste trabalho estão implementados no software “Video Quality Assessment in Java” (jVQA), baseado nas plataformas AviSynth e FFmpeg e que é projetado para personalização e extensibilidade, suportando conteúdo ultra-alta definição “4K” e disponibilizado como código-fonte aberto e livre.
FOTIO, TIOTSOP LOHIC. "Optimizing Perceptual Quality Prediction Models for Multimedia Processing Systems." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2970982.
Повний текст джерелаZhang, Di. "INFORMATION THEORETIC CRITERIA FOR IMAGE QUALITY ASSESSMENT BASED ON NATURAL SCENE STATISTICS." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2842.
Повний текст джерелаThe goal of objective image quality assessment is to introduce a computational quality metric that can predict image or video quality. Many methods have been proposed in the past decades. Traditionally, measurements convert the spatial data into some other feature domains, such as the Fourier domain, and detect the similarity, such as mean square distance or Minkowsky distance, between the test data and the reference or perfect data, however only limited success has been achieved. None of the complicated metrics show any great advantage over other existing metrics.
The common idea shared among many proposed objective quality metrics is that human visual error sensitivities vary in different spatial and temporal frequency and directional channels. In this thesis, image quality assessment is approached by proposing a novel framework to compute the lost information in each channel not the similarities as used in previous methods. Based on natural scene statistics and several image models, an information theoretic framework is designed to compute the perceptual information contained in images and evaluate image quality in the form of entropy.
The thesis is organized as follows. Chapter I give a general introduction about previous work in this research area and a brief description of the human visual system. In Chapter II statistical models for natural scenes are reviewed. Chapter III proposes the core ideas about the computation of the perceptual information contained in the images. In Chapter IV, information theoretic criteria for image quality assessment are defined. Chapter V presents the simulation results in detail. In the last chapter, future direction and improvements of this research are discussed.
R, V. Krishnam Raju Kunadha Raju. "Perceptual Image Quality Prediction Using Region of Interest Based Reduced Reference Metrics Over Wireless Channel." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13631.
Повний текст джерелаHurren, Anne. "The development of a new rating scale for the perceptual assessment of tracheoesophageal voice quality outcome following total laryngectomy." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2538.
Повний текст джерелаLing, Suiyi. "Perceptual representations of structural and geometric information in images : bio-inspired and machine learning approaches : application to visual quality assessment of immersive media." Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4061/document.
Повний текст джерелаThis work aims to better evaluate the perceptual quality of image/video that contains structural and geometric related distortions in the context of immersive multimedia. We propose and explore a hierarchical framework of visual perception for image/video. Inspired by representation mechanism of the visual system, low-level (elementary visual features, e.g. edges), mid-level (intermediate visual patterns, e.g. codebook of edges), and higher-level (abstraction of visual input, e.g. category of distorted edges) image/video representations are investigated for quality assessment. The first part of this thesis addresses the low-level structure and texture related representations. A bilateral filter-based model is first introduced to qualify the respective role of structure and texture information in various assessment tasks (utility, quality . . . ). An image quality/video quality measure is proposed to quantify structure deformation spatially and temporally using new elastic metric. The second part explores mid-level structure related representations. A sketch-token based model and a context tree based model are presented in this part for the image and video quality evaluation. The third part explores higher-level structure related representations. Two machine learning approaches are proposed to learn higher-level representation: a convolutional sparse coding based and a generative adversarial network. Along the thesis, experiments an user studies have been conducted on different databases for different applications where special structure related distortions are observed (FTV, multi-view rendering, omni directional imaging . . . )
Sanches, Silvio Ricardo Rodrigues. "Avaliação objetiva de qualidade de segmentação." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-26062014-111553/.
Повний текст джерелаAssessment of video segmentation quality is a problem seldom investigated by the scientific community. Nevertheless, recent studies presented some objective metrics to evaluate algorithms. Such metrics consider different ways in which segmentation errors occur (perceptual factors) and its parameters are adjusted according to the application for which the segmented frames are intended. In this work: i) we demonstrate empirically that the performance of existing metrics changes according to the segmentation algorithm; ii) we developed a subjective method to evaluate segmentation quality; and iii) we contribute with a new objective metric derived on the basis of experiments from subjective method in order to adjust the parameters of two bilayer segmentation algorithms found in the literature when these algorithms are used for compose scenes in Immersive Teleconference environments.
Horn, Sandra L. "Aggregating Form Accuracy and Percept Frequency to Optimize Rorschach Perceptual Accuracy." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449513233.
Повний текст джерелаReisenhofer, Rafael [Verfasser], Emily [Akademischer Betreuer] King, Emily [Gutachter] King, and Armin [Gutachter] Iske. "Image Analysis via Applied Harmonic Analysis : Perceptual Image Quality Assessment, Visual Servoing, and Feature Detection / Rafael Reisenhofer ; Gutachter: Emily King, Armin Iske ; Betreuer: Emily King." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1169299105/34.
Повний текст джерелаKöppl, Sonja Maria [Verfasser], Christian [Akademischer Betreuer] Wöhler, and Rüdiger [Gutachter] Kays. "Objective assessment of the perceptual quality of HMI-components with a particular focus on the head-up display / Sonja Maria Köppl ; Gutachter: Rüdiger Kays ; Betreuer: Christian Wöhler." Dortmund : Universitätsbibliothek Dortmund, 2017. http://d-nb.info/1153198436/34.
Повний текст джерелаKöppl, Sonja [Verfasser], Christian [Akademischer Betreuer] Wöhler, and Rüdiger [Gutachter] Kays. "Objective assessment of the perceptual quality of HMI-components with a particular focus on the head-up display / Sonja Maria Köppl ; Gutachter: Rüdiger Kays ; Betreuer: Christian Wöhler." Dortmund : Universitätsbibliothek Dortmund, 2017. http://d-nb.info/1153198436/34.
Повний текст джерелаAburas, Akram. "Operating System Based Perceptual Evaluation of Call Quality in Radio Telecommunications Networks. Development of call quality assessment at mobile terminals using the Symbian operating system, comparison with traditional approaches and proposals for a tariff regime relating call charging to perceived speech quality." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5479.
Повний текст джерелаOuni, Sonia. "Evaluation de la qualité des images couleur. Application à la recherche & à l'amélioration des images." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS034.
Повний текст джерелаThe research area in the objective quality assessment of the color images has been a renewed interest in recent years. The work is primarily driven by the advent of digital pictures and additional needs in image coding (compression, transmission, recovery, indexing,...). So far the best evaluation is visual (hence subjective) or by psychophysical techniques or by expert evaluation. Therefore, it is useful, even necessary, to establish criteria and objectives that automatically measures quality scores closest possible quality scores given by the subjective evaluation. We propose, firstly, a new full reference metric to assess the quality of color images, called overall Delta E, based on color appearance and incorporates the features of the human visual system (HVS). Performance was measured in two areas of application compression and restoration. The experiments carried out show a significant correlation between the results and subjective assessment.Then, we propose a new no reference quality assessmenent color images approach based on neural networks: given the multidimensional nature of image quality, a quantification of quality has been proposed, based on a set of attributes forming the descriptor UN (Utility, Naturalness). Accuracy reflects the sharpness and clarity. As for naturality, it reflects the brightness and color. To model the criterion of color, three no reference metrics were defined to detect the dominant color in the image, the proportion of that color and its spatial dispersion. This approach is based on neural networks to mimic the HVS perception. Two variants of this approach have been tried (direct and progressive). The results showed the performance of the progressive variant compared to the direct variant. The application of the proposed approach in two areas: in the context of restoration, this approach has served as a stopping criterion for automatic restoration algorithms. In addition, we have used in a system for estimating the quality of images to automatically detect the type of content in an image degradation. In the context of indexing and image retrieval, the proposed approach was used to introduce the quality of images in the database as an index. The experimental results showed the improvement of system performance image search by content by using the index or by making a quality refinement results with the quality criterion
Hsu, Shih-Yuan, and 徐詩媛. "Image quality assessment based on perceptual quality." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/7b944d.
Повний текст джерела國立臺北科技大學
電機工程系研究所
101
Image quality assessment is to measure the visual difference between two images. In order to make evaluation result in line with the visual quality perceived by the human, it is necessary to make use of the characteristic of the human visual system (HVS) into image quality assessment methods. Most of the literature works focus on how to more effectively compare two images of local information, but ignore the fact that they should have unequal sum-up weighting to the total, as the human vision has different sensitivity in regions with different contents and distortion. This work proposes an image assessment methods based on VIF. At the first, we extract the features of visual sensitivity in images with the Haar wavelet transform and log-Gabor filter, and detect the salient object region with the Laplacian filter, and calculate the distortion region with SSIM. For log-Gabor filter, we apply weighting to the log-Gabor frequency band based on the contrast sensitivity function (CSF). Since VIF assessment is based on the information comparison and not effective in luminance distortion, we take into account the luminance component of SSIM in the image information calculation, to compensate for the weakness of VIF in brightness distortion. The experimental results on image database show that our overall performance and efficiency outperforms the general image quality assessment methods.
Zeng, Kai. "Perceptual Video Quality Assessment and Enhancement." Thesis, 2013. http://hdl.handle.net/10012/7720.
Повний текст джерелаTsai, Cheng-Min, and 蔡政旻. "Perceptual Image Quality Assessment and Eye Movements." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/34435232599978600189.
Повний текст джерела國立雲林科技大學
設計學研究所
104
Three studies were conducted to explore the eye movement responses of subjects assessing perceived image quality. The main purposes of this study were (1) to explore the relationship between the physical attributes of images and the perceived image quality, (2) to explore and analyze eye movement response in a perceived image-quality assessment task, and (3) to determine a fixation map for a perceived image-quality assessment task. The methods and results of these three studies are described as follows. In Study I, 35 images were used. Data on seven observers’ visual assessments of the contrast, saturation, and sharpness of images were collected for analysis. The results showed that, when the image contrast or saturation was increased, the image quality was perceived to be more visually pleasing. By contrast, when the sharpness of an image was increased or decreased, the image quality was perceived to be the least pleasing. The results of a canonical correlation analysis revealed that physical attributes explained 57.94% of the perceived image quality. In Study II, 30 observers assessed 11 images, and their eye movement responses were analyzed to determine how the responses affected their perceptions of the image quality. The results showed that their subjective assessment of perceived image color quality exhibited a highly positive correlation with global perceived image quality. Additionally, the subjective assessment of perceived image color quality increased with the image color gamut. Eye movement data for the perceived image-color quality assessment correlated positively with the eye movement data for the perceived image-quality assessment. In observers who spent less time assessing the images, the information carried by their eye movement facilitated their predicting perceived image-color quality assessments more accurately and consistently compared with their predictions of perceived image-quality assessments. At a higher amplitude of saccades, the information carried by the eye movement assessment facilitated predictions of the perceived image quality. In Study III, two visual assessment experiments were conducted. In total, 45 observers (30 in Experiment 1, 15 in Experiment 2) assessed 17 images (11 in Experiment 1, 6 in Experiment 2), and their eye movements were analyzed. The results showed that the CIEL*a*b color difference formula could facilitate easily understanding and computing the differences in a high number of fixation maps. The results from the two experiments were consistent, indicating that eye-tracking data are robust for predicting image quality. Observers tend to focus on either human faces or animal eyes. This study also shows that observers tend to ignore blue skies, grass, and foliage in landscape images. The central region attracted more attention than did the background or other objects in the images studied. All results have been applied to TTLA’s projects, which included developing and designing integrated image-processors for digital liquid crystal display televisions.
Yen, Ting-Yu, and 顏廷宇. "Objective Assessment of Speech Quality by Perceptual Features." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/40465576549134580524.
Повний текст джерела國立交通大學
電信工程系所
96
In this study, a joint spectro-temporal auditory model was utilized to assess speech quality objectively. In this model, the first stage is to mimic early cochlear functions of the spectrum estimation and the second stage is to mimic cortical functions of the multi-dimensional spectrum analysis. The goal of this study is to predict subjective mean opinion score (MOS). Objective speech quality assessment can be done by two methods:intrusive and non-intrusive. In this study, firstly, we observe and analyze patterns of the clean speech, the noisy speech with different background noise, and the degraded speech through different codecs at two auditory stages. Secondly, we will derive an objective estimate of the MOS from data-driven perceptual parameters which are believed to reflect people’s judgment on speech quality. Four perceptual parameters considered are intelligibility, naturalness, and pitch distortion. Finally, we use multiple regression analysis to combine the relationship between speech quality and these perceptual parameters, and then obtain our predicted MOS. We then demonstrate the MOS can be characterized quickly and reliably by these three perceptual features.
"Perceptual quality assessment and processing for visual signals." 2013. http://library.cuhk.edu.hk/record=b5549788.
Повний текст джерела第一部分主要集中在具有完全套考原始圖像的圖像質量評價。首先我們研究人類視覺系統的特征。具體說來,視覺在結構化失真上面的水平特性和顯著特征會被建模然后應用到結構相似度(SSIM)這個衡量標準上。實驗顯示我們的方法明顯的提高了衡量標準典主觀評價的相似度。由這個質量衡量標準的啟發,我們設計了一個主觀圖像壓縮的方法。其中我們提出了一個自適應的塊大小的超分辨率算法指導的下采樣的算法。實驗結果證明提出的圖像壓縮算法無論在主觀還是在客觀層面都構建了高質量的圖像。
第二個部分的工作主要討論具有完全參考原始視頻的視頻質量評價。考慮到人類視覺系統的特征,比如時空域的對此敏感函數,眼球的移動,紋理的遮掩特性,空間域的一致性,時間域的協調性,不同塊變換的特性,我們設計了一個自適應塊大小的失真閾值的模型。實驗證明,我們提出的失真閾值模型能夠更精確的描迷人類視覺系統的特性。基于這個自適應塊大小的失真閾值模型,我們設計了一個簡單的主觀質量評價標準。在公共的圓像以及視頻的主觀數據庫上的測試結果證明了這個簡單的評價標準的有效性。因此,我們把這個簡單的質量標準應用于視頻編碼系統中。它可以在同樣的碼率下提供更高主觀質量的視頻。
第三部分我們討論具有部分參考信息的圖像質量評價。我們通過描迷重組后的離散余弦變換域的系數的統計分布來衡量圖像的主觀質量。提出的評價標準發掘了相鄰的離散余弦系數的相同統計特性,相鄰的重組離散余弦系數的互信息,以及圖像的能量在不同頻率下的分布。實驗結果證明我們提出的質量標準河以超越其他的具有部分參考信息的質量評價標準,甚至還超過了具有完全參考信息的質量評價標準。而且,提取的特征很容易被編碼以及隱藏到圖像中以便于在圖像通訊中進行質量監控。
第四部分我們討論具有部分參考信息的視頻質量評價。我們提取的特征可以很好的描迷空間域的信息失,和時間域的相鄰兩幀間的直方圖的統計特性。在視頻主觀質量的數據庫上的實驗結果,也證明了提出的方法河以超越其他代表性的視頻質量評價標準,甚至是具有完全參考信息的質量評價標準, 譬如PSNR以及SSIM 。我們的方法只需要很少的特征來描迷每一幀視頻圖像。對于每一幀圖像,一個特征用于描迷空間域的特點,另外三個特征用于描述時間域的特點。考慮到計算的復雜度以及壓縮特征所需要的碼率,提出的方法河以很簡單的在視頻的傳輸過程中監控視頻的質量。
之前的四部分提到的主觀質量評價標準主要集中在傳統的失真上面, 譬如JPEG 圖像壓縮, H.264視頻壓縮。在最后一部分,我們討論在圖像跟視頻的retargeting過程中的失真。現如今,隨著消費者電子的發展,視覺信號需要在不同分辨率的顯示設備上進行通訊交互。因此, retargeting的算法把同一個原始圖像適應于不同的分辨率的顯示設備。這樣的過程就會引入圖像的失真。我們研究了對于retargeting圖像主觀質量的測試者的分數,從三個方面進行討論測試者對于retargeting圖像失真的反應.圖像retargeting的尺度,圖像retargeting的算法,原始圖像的內容特性。通過大量的主觀實驗測試,我們構建了一個關于圖像retargeting的主觀數據庫。基于這個主觀數據庫,我們評價以及分析了幾個具有代表性的質量評價標準。
Visual signals, including images, videos, etc., are affected by a wide variety of distortions during acquisition, compression, storage, processing, transmission, and reproduction processes, which result in perceptual quality degradation. As a result, perceptual quality assessment plays a very important role in today's visual signal processing and communication systems. In this thesis, quality assessment algorithms for evaluating the visual signal perceptual quality, as well as the applications on visual signal processing and communications, are investigated. The work consists of five parts as briefly summarized below.
The first part focuses on the full-reference (FR) image quality assessment. The properties of the human visual system (HVS) are firstly investigated. Specifically, the visual horizontal effect (HE) and saliency properties over the structural distortions are modelled and incorporated into the structure similarity index (SSIM). Experimental results show significantly improved performance in matching the subjective ratings. Inspired by the developed FR image metric, a perceptual image compression scheme is developed, where the adaptive block-based super-resolution directed down-sampling is proposed. Experimental results demonstrated that the proposed image compression scheme can produce higher quality images in terms of both objective and subjective qualities, compared with the existing methods.
The second part concerns the FR video quality assessment. The adaptive block-size transform (ABT) based just-noticeable difference (JND) for visual signals is investigated by considering the HVS characteristics, e.g., spatio-temporal contrast sensitivity function (CSF), eye movement, texture masking, spatial coherence, temporal consistency, properties of different block-size transforms, etc. It is verified that the developed ABT based JND can more accurately depict the HVS property, compared with the state-of-the-art JND models. The ABT based JND is thereby utilized to develop a simple perceptual quality metric for visual signals. Validations on the image and video subjective quality databases proved its effectiveness. As a result, the developed perceptual quality metric is employed for perceptual video coding, which can deliver video sequences of higher perceptual quality at the same bit-rates.
The third part discusses the reduced-reference (RR) image quality assessment, which is developed by statistically modelling the coe cient distribution in the reorganized discrete cosine transform (RDCT) domain. The proposed RR metric exploits the identical statistical nature of the adjacent DCT coefficients, the mutual information (MI) relationship between adjacent RDCT coefficients, and the image energy distribution among different frequency components. Experimental results demonstrate that the proposed metric outperforms the representative RR image quality metrics, and even the FR quality metric, i.e., peak signal to noise ratio (PSNR). Furthermore, the extracted RR features can be easily encoded and embedded into the distorted images for quality monitoring during image communications.
The fourth part investigates the RR video quality assessment. The RR features are extracted to exploit the spatial information loss and the temporal statistical characteristics of the inter-frame histogram. Evaluations on the video subjective quality databases demonstrate that the proposed method outperforms the representative RR video quality metrics, and even the FR metrics, such as PSNR, SSIM in matching the subjective ratings. Furthermore, only a small number of RR features is required to represent the original video sequence (each frame requires only 1 and 3 parameters to depict the spatial and temporal characteristics, respectively). By considering the computational complexity and the bit-rates for extracting and representing the RR features, the proposed RR quality metric can be utilized for quality monitoring during video transmissions, where the RR features for perceptual quality analysis can be easily embedded into the videos or transmitted through an ancillary data channel.
The aforementioned perceptual quality metrics focus on the traditional distortions, such as JPEG image compression noise, H.264 video compression noise, and so on. In the last part, we investigate the distortions introduced during the image and video retargeting process. Nowadays, with the development of the consumer electronics, more and more visual signals have to communicate between different display devices of different resolutions. The retargeting algorithm is employed to adapt a source image of one resolution to be displayed in a device of a different resolution, which may introduce distortions during the retargeting process. We investigate the subjective responses on the perceptual qualities of the retargeted images, and discuss the subjective results from three perspectives, i.e., retargeting scales, retargeting methods, and source image content attributes. An image retargeting subjective quality database is built by performing a large-scale subjective study of image retargeting quality on a collection of retargeted images. Based on the built database, several representative quality metrics for retargeted images are evaluated and discussed.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Ma, Lin.
"December 2012."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 185-197).
Abstract also in Chinese.
Dedication --- p.ii
Acknowledgments --- p.iii
Abstract --- p.viii
Publications --- p.xi
Nomenclature --- p.xvii
Contents --- p.xxiv
List of Figures --- p.xxviii
List of Tables --- p.xxx
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Motivation and Objectives --- p.1
Chapter 1.2 --- Subjective Perceptual Quality Assessment --- p.5
Chapter 1.3 --- Objective Perceptual Quality Assessment --- p.10
Chapter 1.3.1 --- Visual Modelling Approach --- p.10
Chapter 1.3.2 --- Engineering Modelling Approach --- p.15
Chapter 1.3.3 --- Perceptual Subjective Quality Databases --- p.19
Chapter 1.3.4 --- Performance Evaluation --- p.21
Chapter 1.4 --- Thesis Contributions --- p.22
Chapter 1.5 --- Organization of the Thesis --- p.24
Chapter I --- Full Reference Quality Assessment --- p.26
Chapter 2 --- Full Reference Image Quality Assessment --- p.27
Chapter 2.1 --- Visual Horizontal Effect for Image Quality Assessment --- p.27
Chapter 2.1.1 --- Introduction --- p.27
Chapter 2.1.2 --- Proposed Image Quality Assessment Framework --- p.28
Chapter 2.1.3 --- Experimental Results --- p.34
Chapter 2.1.4 --- Conclusion --- p.36
Chapter 2.2 --- Image Compression via Adaptive Block-Based Super-Resolution Directed Down-Sampling --- p.37
Chapter 2.2.1 --- Introduction --- p.37
Chapter 2.2.2 --- The Proposed Image Compression Framework --- p.38
Chapter 2.2.3 --- Experimental Results --- p.42
Chapter 2.2.4 --- Conclusion --- p.45
Chapter 3 --- Full Reference Video Quality Assessment --- p.46
Chapter 3.1 --- Adaptive Block-size Transform based Just-Noticeable Dfference Model for Visual Signals --- p.46
Chapter 3.1.1 --- Introduction --- p.46
Chapter 3.1.2 --- JND Model based on Transforms of Different Block Sizes --- p.48
Chapter 3.1.3 --- Selection Strategy Between Transforms of Different Block Sizes --- p.53
Chapter 3.1.4 --- JND Model Evaluation --- p.56
Chapter 3.1.5 --- Conclusion --- p.60
Chapter 3.2 --- Perceptual Quality Assessment --- p.60
Chapter 3.2.1 --- Experimental Results --- p.62
Chapter 3.2.2 --- Conclusion --- p.64
Chapter 3.3 --- Motion Trajectory Based Visual Saliency for Video Quality Assessment --- p.65
Chapter 3.3.1 --- Motion Trajectory based Visual Saliency for VQA --- p.66
Chapter 3.3.2 --- New Quaternion Representation (QR) for Each frame --- p.66
Chapter 3.3.3 --- Saliency Map Construction by QR --- p.67
Chapter 3.3.4 --- Incorporating Visual Saliency with VQAs --- p.68
Chapter 3.3.5 --- Experimental Results --- p.69
Chapter 3.3.6 --- Conclusion --- p.72
Chapter 3.4 --- Perceptual Video Coding --- p.72
Chapter 3.4.1 --- Experimental Results --- p.75
Chapter 3.4.2 --- Conclusion --- p.76
Chapter II --- Reduced Reference Quality Assessment --- p.77
Chapter 4 --- Reduced Reference Image Quality Assessment --- p.78
Chapter 4.1 --- Introduction --- p.78
Chapter 4.2 --- Reorganization Strategy of DCT Coefficients --- p.81
Chapter 4.3 --- Relationship Analysis of Intra and Inter RDCT subbands --- p.83
Chapter 4.4 --- Reduced Reference Feature Extraction in Sender Side --- p.88
Chapter 4.4.1 --- Intra RDCT Subband Modeling --- p.89
Chapter 4.4.2 --- Inter RDCT Subband Modeling --- p.91
Chapter 4.4.3 --- Image Frequency Feature --- p.92
Chapter 4.5 --- Perceptual Quality Analysis in the Receiver Side --- p.95
Chapter 4.5.1 --- Intra RDCT Feature Difference Analysis --- p.95
Chapter 4.5.2 --- Inter RDCT Feature Difference Analysis --- p.96
Chapter 4.5.3 --- Image Frequency Feature Difference Analysis --- p.96
Chapter 4.6 --- Experimental Results --- p.98
Chapter 4.6.1 --- Efficiency of the DCT Reorganization Strategy --- p.98
Chapter 4.6.2 --- Performance of the Proposed RR IQA --- p.99
Chapter 4.6.3 --- Performance of the Proposed RR IQA over Each Individual Distortion Type --- p.105
Chapter 4.6.4 --- Statistical Significance --- p.107
Chapter 4.6.5 --- Performance Analysis of Each Component --- p.109
Chapter 4.7 --- Conclusion --- p.111
Chapter 5 --- Reduced Reference Video Quality Assessment --- p.113
Chapter 5.1 --- Introduction --- p.113
Chapter 5.2 --- Proposed Reduced Reference Video Quality Metric --- p.114
Chapter 5.2.1 --- Reduced Reference Feature Extraction from Spatial Perspective --- p.116
Chapter 5.2.2 --- Reduced Reference Feature Extraction from Temporal Perspective --- p.118
Chapter 5.2.3 --- Visual Quality Analysis in Receiver Side --- p.121
Chapter 5.3 --- Experimental Results --- p.123
Chapter 5.3.1 --- Consistency Test of the Proposed RR VQA over Compressed Video Sequences --- p.124
Chapter 5.3.2 --- Consistency Test of the Proposed RR VQA over Video Sequences with Simulated Distortions --- p.126
Chapter 5.3.3 --- Performance Evaluation of the Proposed RR VQA on Compressed Video Sequences --- p.129
Chapter 5.3.4 --- Performance Evaluation of the Proposed RR VQA on Video Sequences Containing Transmission Distortions --- p.133
Chapter 5.3.5 --- Performance Analysis of Each Component --- p.135
Chapter 5.4 --- Conclusion --- p.137
Chapter III --- Retargeted Visual Signal Quality Assessment --- p.138
Chapter 6 --- Image Retargeting Perceptual Quality Assessment --- p.139
Chapter 6.1 --- Introduction --- p.139
Chapter 6.2 --- Preparation of Database Building --- p.142
Chapter 6.2.1 --- Source Image --- p.142
Chapter 6.2.2 --- Retargeting Methods --- p.143
Chapter 6.2.3 --- Subjective Testing --- p.146
Chapter 6.3 --- Data Processing and Analysis for the Database --- p.150
Chapter 6.3.1 --- Processing of Subjective Ratings --- p.150
Chapter 6.3.2 --- Analysis and Discussion of the Subjective Ratings --- p.153
Chapter 6.4 --- Objective Quality Metric for Retargeted Images --- p.162
Chapter 6.4.1 --- Quality Metric Performances on the Constructed Image Retargeting Database --- p.162
Chapter 6.4.2 --- Subjective Analysis of the Shape Distortion and Content Information Loss --- p.165
Chapter 6.4.3 --- Discussion --- p.167
Chapter 6.5 --- Conclusion --- p.169
Chapter 7 --- Conclusions --- p.170
Chapter 7.1 --- Conclusion --- p.170
Chapter 7.2 --- Future Work --- p.173
Chapter A --- Attributes of the Source Image --- p.176
Chapter B --- Retargeted Image Name and the Corresponding Number --- p.179
Chapter C --- Source Image Name and the Corresponding Number --- p.183
Bibliography --- p.185
WAN, KUAN-HUNG, and 萬冠宏. "Color Image Quality Assessment Based on Perceptual Properties." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3778me.
Повний текст джерела國立臺北科技大學
電機工程研究所
105
Image Quality Assessment (IQA) aims to predict the quality of distorted images when viewed by human observers. Besides quantifying the distortions of an image, characteristics of Human Visual System (HVS) should also be taken into account so that predictions can be in line with human judgements. Existing IQA metrics mostly focus on designing an accurate local quality estimation; whereas the global quality score for a distorted image is often obtained by averaging local quality scores, overlooking the individual importance of local regions. Moreover, most IQA metrics can only assess grayscale images, hence chrominance data is usually omitted by assessment processes. This work aims to improve the performance of VIF by incorporating chrominance channels into the algorithm. Perceptual color difference is measured by a novel superpixel-based CIEDE2000 extension. Color difference and visual saliency are used as pooling weights to determine the different importance of each local quality estimation of an image. Extensive experiments performed on six benchmark IQA databases show that the proposed NEWSS-VIF achieves promising results for estimating perceptual quality of color images.
Kannan, Vignesh. "Perceptual Quality Assessment of Lowlight Restored and Authentically Distorted Images." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5792.
Повний текст джерелаYang, Hao-Po, and 楊皓博. "3D Video Quality Assessment based on the 3D Visual Perceptual." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73566966956701440490.
Повний текст джерела國立暨南國際大學
電機工程學系
102
In recently years, three-dimensional (3D) video is very popular. Most existing 3D video quality metrics uses traditional 2D image quality assessment (IQA) to judge the quality of 3D video. However, 2D IQA does not sufficient render human judgment for 3D video, since 3D image have some different characteristics with 2D video. Therefore, this thesis proposes a new 3D video quality assessment based on 3D visual perceptual for texture and depth image to measure the quality of 3D videos. As observe in this research, the 3D distortions can be classified to depth distortions and texture distortions. In the aspect of 3D videos, depth information is the main factor of effecting 3D watching experience, if depth information is distorted will make 3D watching discomfort. The texture distortions include ghost effect; contour artifacts; compressed texture quality decadence. In addition, the distortions of texture and depth image are also important like compressed distortion, after compressed the quality of texture and depth map will be lowed. In this thesis, the proposed assessment metric uses the edge information to evaluate the ghost effect and contour artifacts. For compressed texture quality decadence, this thesis uses 2D quality metric to evaluate the quality and consider the effect of object shift. Since the characteristics of depth map are different with color image. Therefore, this thesis chooses 2D quality metric IWSSIM to evaluate the quality in compressed depth map. The experimental results show that the proposed metric compare to 2D Quality metrics and other reference metrics is more suitable to the human perception, as demonstrated by Pearson correlation coefficient (PLCC) obtained from subjective score and objective score. The proposed 3D video quality assessment is based 3D visual perceptual. It makes the quality assessment result more approach the 3D experience of viewer.
"Perceptual-Based Locally Adaptive Noise and Blur Detection." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.38426.
Повний текст джерелаDissertation/Thesis
Doctoral Dissertation Electrical Engineering 2016
Kumcu, A., L. Platisa, H. Chen, Amber J. Gislason-Lee, A. G. Davies, P. Schelkens, Y. Taeymans, and W. Philips. "Selecting stimuli parameters for video quality studies based on perceptual similarity distances." 2015. http://hdl.handle.net/10454/16977.
Повний текст джерелаThis work presents a methodology to optimize the selection of multiple parameter levels of an image acquisition, degradation, or post-processing process applied to stimuli intended to be used in a subjective image or video quality assessment (QA) study. It is known that processing parameters (e.g. compression bit-rate) or techni- cal quality measures (e.g. peak signal-to-noise ratio, PSNR) are often non-linearly related to human quality judgment, and the model of either relationship may not be known in advance. Using these approaches to select parameter levels may lead to an inaccurate estimate of the relationship between the parameter and subjective quality judgments – the system’s quality model. To overcome this, we propose a method for modeling the rela- tionship between parameter levels and perceived quality distances using a paired comparison parameter selection procedure in which subjects judge the perceived similarity in quality. Our goal is to enable the selection of evenly sampled parameter levels within the considered quality range for use in a subjective QA study. This approach is tested on two applications: (1) selection of compression levels for laparoscopic surgery video QA study, and (2) selection of dose levels for an interventional X-ray QA study. Subjective scores, obtained from the follow-up single stimulus QA experiments conducted with expert subjects who evaluated the selected bit-rates and dose levels, were roughly equidistant in the perceptual quality space - as intended. These results suggest that a similarity judgment task can help select parameter values corresponding to desired subjective quality levels.
Parts of this work were performed within the Telesurgery project (co-funded by iMinds, a digital research institute founded by the Flemish Government; project partners are Unilabs Teleradiology, SDNsquare and Barco, with project support from IWT) and the PANORAMA project (co-funded by grants from Belgium, Italy, France, the Netherlands, the United Kingdom, and the ENIAC Joint Undertaking).
Ma, Kede. "Objective Quality Assessment and Optimization for High Dynamic Range Image Tone Mapping." Thesis, 2014. http://hdl.handle.net/10012/8517.
Повний текст джерелаRohdenburg, Thomas [Verfasser]. "Development and objective perceptual quality assessment of monaural and binaural noise reduction schemes for hearing aids / Thomas Rohdenburg." 2009. http://d-nb.info/996773150/34.
Повний текст джерелаRehman, Abdul. "SSIM-Inspired Quality Assessment, Compression, and Processing for Visual Communications." Thesis, 2013. http://hdl.handle.net/10012/7763.
Повний текст джерелаBrunet, Dominique. "A Study of the Structural Similarity Image Quality Measure with Applications to Image Processing." Thesis, 2012. http://hdl.handle.net/10012/6982.
Повний текст джерелаvan, Kasteren Anouk. "The Contribution of Eye Tracking to Quality of Experience Assessment of 360-degree video." Thesis, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-39963.
Повний текст джерелаGIANNITRAPANI, PAOLO. "Study of the subjective effects of blur on the vision of natural images: an abstract, physical parametric model for Image Quality Assessment." Doctoral thesis, 2022. http://hdl.handle.net/11573/1637467.
Повний текст джерела